Yep, Corretja makes a good case for Roland Garros, and Henman is undoubtedly his equivalent at Wimbledon - true, he's never made the final, but he's one of the leading contenders and always gets to the latter stages only to be snuffed out by the eventual champion. Roland Garros seems to be a great place for old champions and former greats of the game to make a brief comeback by reaching the final, only to lose out to a better known and younger player; Stich in 96, Bruguera in 97, Medvedev in 99.
Rios and Enqvist have both made only one Slam final, at the AO in 98 and 99 respectively, and both times they were soundly beaten not just by their opponent but by their nerves as well. Rios had a horrendous choke against Korda, all Petr had to do was keep the ball in play and wait for the errors, and Kafelnikov cleaned Enqvist up very handily after losing the first set. Clement and Schuettler's one-sided defeats at the hands of Agassi were almost inevitable, even though we can't say for certain whether they won't reach more Grand Slam finals - Schuettler's game is a carbon copy of Hewitt's, and look where it's gotten the world no. 1 to....
Philippoussis and Todd Martin are undoubtedly the major losers at Wimbledon and the US Open - both beaten in the final of Flushing Meadows, and both having a brilliant chance to make it to the Wimbledon final but falling at the penultimate hurdle. I don't remember anything about the Scud's brilliant match against Sampras before he had to retire, perhaps I wasn't watching Wimbledon that year, but that was a definite opportunity. It's true, however, that Todd Martin wasn't really unlucky, he just had some horrendous chokes - I can imagine Agassi fighting back as he did in 2000, but Martin actually led 5-1 serving for the match against Washington in 96, had matchpoint at 5-3 and lost it 10-8 in the end. He'd certainly have given Krajicek a far tougher match than Malivai did in the end.